Analysis Of The Niche And Interspecific Association Of Vegetations Under Mixed Forest In The Northern Mountain Of Hebei Province

The research object is based on the mixed forest in the northern mountain of Hebei province, through to investigate the shrub layer and herb layer species. The shrub species include Ulmus macrocarpa, Cornus alba, Lespedeza bicolor, Lonicera Japonica, Spiraea solicitous, Rubus caricaturist and Rhododendron Micranthum. The main species of herb layer are Carex rigescens, Artemisia sacrorum, Leymus chinensis, Dendranthema chanetii, etc. The paper anlyses from niche and interspecific association. Here are the major conclusion:(1) niche width: In the shrub layer, LNB value of niche width of Lespedeza bicolor, Spiraea solicitous and Rhododendron Micranthum are more than 1, HNB values of Cornus alba, Lespedeza bicolor, Lonicera Japonica and Spiraea solicitous are above 0.9000. The LNB and HNB values of niche width of Lonicera Japonica and Rubus caricaturist are 0.In the herb layer, LNB and HNB values of niche width of 11 plant are 0, including Scutellavia scordifolia, Athyrium sinense, Patrinia heterophylla, Rabdosia serra (Maxim.), Brassicaceae sisymbrium, Galium verum, Cynoglossum Officinale, Chenopodium album, Wedelia trilobata, Plantago asiatica and Ixeris sonchifolia. The LNB value greater than 1 and HNB value greater than 0.9000 are Carex rigescens, Dendranthema chanetii, Astragalus membranaceus, Sanguisorba officinalis, PoaannuaL, etc. LNB value of species of less than 1 greater than 0.5000 and HNB less than 0.9000 more than 0.8000 are Bidens pilosa, Rubia cordifolia, Asparagus schoberioides, Geranium wilfordii, Setaira viridis, etc. LNB value of species less than 0.5000 greater than 0.2000 and HNB less than 0.8000 more than 0.6000 are Polygonum hydropiper, Dontostemon dentatus, Medicago ruthenica, etc.(2) niche overlap value: In the shrub layer, the niche overlap value of 8 specieses are 0, including Ulmus macrocarpa and Lonicera Japonica, Cornus alba and Lespedeza bicolor, Lonicera Japonica and Rubus caricaturist, etc. The niche overlap value of 5 species are larger, including Lespedeza bicolor and Spiraea solicitous, Lespedeza bicolor and Lonicera Japonica, Ulmus macrocarpa and Spiraea solicitous, Lespedeza bicolor and Rubus caricaturist, Lespedeza bicolor and Rhododendron Micranthum.In the herb layer, 62.59% species of niche overlap value are 0. The specieses proportion of niche overlap in 0.00~0.20 range is 23.31%. The species of niche overlap valuesin 0.80~1.00 range has the smallest proportion, is 0.13%.(3) test of the overall association between species: VR more than 1 in the shrub layer, the overall association showed positive correlation. VR less than 1 in the herb layer, the overall association showed negative correlation. Using statistic W test on the determination results, shrub and herb species show significant association indicating that communities is in the steady state.(4) Chi-square test: The ratio of positive and negative coupling number in the shrub layer is 3:4. Very significant, significant and independent specieses respectively have 11 pairs, 2 pairs and 8 pairs. In the herb layer, the positive associations are 430 pairs; the negative associations are 1166 pairs. Very significant, significant and independent specieses respectively have 1231 pairs, 80 pairs and 285 pairs.PC: The PC value is an indicator which is used to determine the species positive association level. On the whole, the association between the species is low in the shrub. 8 specieses of PC value are 0.0000, it is show that no correlation between the species. The remaining 13 specieses of the PC are in 0.0250 ~ 0.2439 range, the positive connection degree increased gradually. In the herb layer, 1000 specieses of PC value are 0.0000. Only 1 pairs of PC value is 1, it is Galium verum and Rabdosia serra (Maxim.), that the relational degree is the largest and connecte closely. PC values greater than 0.5 is only 6 in the herb layer, so PC value is generally small.AC: In the shrub layer, 12 specieses are positive connection and 9 specieses are negative association. The ratio of positive and negative coupling in the herb layer is 1:2.71. The proportion of negative coupling is larger, illustrating that negative association between specieses is strong in the herb layer.